(1) Field of the invention
The present invention relates to a data transmission system and in particular, to a circuit device for obtaining a clock pulse synchronized to a data signal received at a receiving side.
(b 2) Description of the Prior Art
In a data transmission system such as a time division PCM data transmission system, the data signal is produced at and transmitted from a transmitting side under control of a clock pulse having a constant repetition frequency. A receiving side also uses a clock pulse for obtaining data from the received signal. The clock pulse of the receiving side must be synchronized to the received data signal.
In transmission of a data signal from a transmitting side to a receiving side through a transmission cable, the clock pulse of the receiving side is not synchronous to the data signal received at the receiving side due to the difference in clock phase between the transmitting side and the receiving side as well as the propagation delay of the data signal on the transmission cable.